A recognised problem in the construction of dynamo electric machine rotors, is that the rotor windings, which encircle the radially extending poles of the rotor, must be held securely within the rotor core not only against vibration, but more particularly against centrifugal forces which are exerted on the windings throwing the windings radially outwardly as the rotor rotates. These problems are recognised in high speed machines where the rotor rotates very rapidly, and are exacerbated by increasing the rotor diameter for example to increase the power output of a generator.
The poles of the core of the rotor extend radially outwardly with respect to the rotational axis of the rotor, and as the poles are of substantially constant thickness (measured in a circumferential direction) the rotor slots (the gaps between circumferentially adjacent poles) increase in width from a minimum adjacent the roots of the poles towards a maximum adjacent the radially outermost ends of the poles. The windings encircling the poles occupy part of the tapering slot between adjacent poles, and it is usual to provide the free ends of the poles with circumferentially extending pole tips which overlie, at least in part, the windings.
It is known to locate the windings radially by means of a slot closure member usually referred to as a wedge, which fits across the gap between circumferentially adjacent poles, the member seating beneath the mutually presented pole tips of the two adjacent poles and engaging the radially outward ends of the windings between adjacent poles so as to distribute the circumferential loading, in use, imposed upon the closure member by the windings, into the pole tips. Furthermore, it is also known to introduce a spacer of V-shaped cross-section between the adjacent windings and beneath the aforementioned wedge, to assist in circumferential location of the windings.